Method of and apparatus for heat-treating sheets and plates



May 6, 1924.

R. E. ZIMMERMAN METHOD OF AND APPARATUS FOR HEAT TREATING SHEETS AND PLATES Filed June 25, 1923 4 Sheets-Sheet 1 Inventor: furua E Z/m/msemew,

Vines-96$ 1,493,140 R. E. ZIMM E RMAN METHOD OF AND APPARATUS FOR HEAT TREATING SHEETS AND PLATES Filed June 25, 1923 4 Sheets-Sheet an, ::E 1.

v um gm M May a, 1924. 1,493,140-

R. E. ZIMMERMAN I METHOD OF AND APPARATUS FOR HEAT TREATING SHEETS AND PLATES Filed June 25 1923 4 Sheets-Sheet 5 May 6,1924,

R. E. ZlMMERMAN METHOD OF AND APPARATUS FOR HEAT TREATING SHEETS AND PLATES Filed June 25, 1925 4 Shefcs-Sheet 4 T 0 all whome't may concern:

Patented h lay 6, i924.

. hearse stares crease RUFUS E. ZIMMERMAN, 0F PITTSBUBGH, PENNSYLVANIA, ASSIGZNOR TO AMEmIflAN SHEET AND TIN FLATE COMPANY OF PITWBURGH, PENNSYLVANIA, A CORIGEA- TIQN 0E NEW JERSEY.

METHOD 6F AND APPARATUS BOB EMT-TREATING- SHEETS AND JPLAT'ESS.

Application filed June 25, 1923. Serial No. 647,576.

Be it known that I, Burns E. ZIMMER- MAN, a citizen of the United States, and resident of Pittsburgh, in the county of Allegheny and State of Pennsylvania, have invented certain new and useful Improvemerits in a Method of and Apparatus for Heat-Treating Sheets and Plates, of which the following is a specification.

This invention relates to an improved method of and apparatus for heat treating rolled steel sheets and plates, and is an improvement over the method described in the patent to George A. White, No. ia se i, dated June 29. 1915. As described in the White patent and as practiced, the method heretofore consisted in passing cold plates into a. heat treating furnace having a relatively narrow heating chamber so that but a small part of the sheet or plate is heated at a time. That is, successive, constantly changing portions of the sheets or plates are passed through the heating zone of the furnace and heated to a temperature of from 1600 degrees to 2200 degrees Fahrenheit and then cooled.

The "White method has proved a success in every Way with the exception that movement of the plates was very slow, since they had to remain over the heating zone of the furnace for a sufficient length of time to become heated to the high temperature required to anneal them.

In open annealing as usually conducted, in which all portions of a plate are heated simultaneously to an annealing temperature, a high elastic limit and high ultimate. strength with low ductility is obtained, while in box. annealing sheets a low elastic limit and low ultimate strength with high ductility is obtained. W'hite discovered that by heating. only small portions of the plates,

successively, to an annealing temperature" and allowing them to cool a plate is obtained having the high ductility attained in-- box annealing without materially reducing the elastic limit and ultimate strength characteristic of open annealed sheets or plates.

The present applicant has discovered that the White method may he materiallyim proved hypreheatingthe plates to a point below the criticai. ran' -e of temperature, that is, below approziircatly 1250 degrees F. and

then passing them directly into the heat treating or annealing furnace for heating the successive sections of the plates to a temperature of from 1600 to 2200 degrees F. for annealing them.

The result of the present invention is to materially increase the speed atwhich lates can be annealed by the White metho In fact, tests show that the number of plates treated in a given time can be more than doubled, Without in any Way reducing the quality of the plates.

The apparatus for carrying out the present method is illustrated in the accompanydrawings, in whichingr igure 1 is a side elevationyof heating letter B designates the heat treating furnace for heat treating or annealing the preheated sheets or plates.

The furnace A is longer than it is Wide and comprises a bottom wall 2,'end Wall 3, side Walls 4 and an arched top Wall 5 made of bricks or other refractory material. A suitable metal reinforcing framework. consisting of huck stays 6, longitudinal girders 7. tie rods 8', and metal shell 9, is provided to support and strengthen the refractory walls as is common in furnace constructions.

I The furnace A is supported over a pit 10, having'a concrete or other similar surrounding wall 11.

vThe space between the bottom and top walls 2 and 5. respectively forms a heating ice gig;

trained over sprockets 24 on the shafts 16,

16 and 18', respectively, and under idler sl'ieaves mounted on stub shafts 26. One of the sheaves. 25 is arranged below the sprockets 24 intermediate the ends of the furnace and the others are arranged altei= nately with the sprockets and on line therewith.

A plurality of combustion chambers 27 are formed in the bottom wall 2 and extend inwardly from the side walls toward the center thereof, the inner ends opening up Wardly into the heating chamber 12. outer ends of the chambers 27 are contracted to form burner ports 28 in which gaseous or liquid fuel owners 29 are mounted. When desired, powdered coal or other fuel may be employed in operating the furnace;

-he combustion chambers 27 on one side of the furnace-are staggered with relation to the chambers on the other side, and al ternately arranged with respect to the clia1n-, bars 27 are air circulation chambers 30- wbich extend into the bottom wall 2 from the side walls of the furnace and have their outer ends open to the atmosphere, forming means wherebp the brickwork is cooled and the temperature equalized.

The ends of the furnace A are open to form inlet and outlet ports 32 am 33, respectively, the outlet port opening directly into the heat treating furnace ll.

. The heat treating furnace ll is arranged across the outlet port 3'3 of the furnace A and is of materially greater length transversely than it is longitudinally of the fur nace A.

The furnace l3 comprises the usual metal reinforcing framework and metal shell 36, and brick bottom wall 37, end walls side walls 39, and top wall 40. The top wall 40 is suspended from the framework 35 by suspension rods 4-1.

The side walls 39 are spaced a relatively small distance apart, forming a narrow chamber, and the top wall is inclined. downwardly from each end toward the center of the furnace l or an appreciable distance while the bottom wall is elevated adjacent each end to form combustion chambers 42, which chambers are provided with bailles l3 and M adjacent their inner ends. The portion vof the chamber or space between the combustion chambers forms a heating Cflflm bar 44 in which the successive portions of the plates are heated to an annealing temperature. Suitable burner ports are formed in the lower portionot the fr nt side The M naeaiao furnace B is symmetrical about the center line X--X.

The side walls 39 are provided with inletand outlet ports -18 and 49, respectively, the inlet port 48 communicatingdirectly with the outlet port 33 of the furnace A.

The forward ends of the plates to be treated are adapted to be moved through the furnace and into the bite of pinch rollers 50 by the convoyer chains 14. The pinch rollers 50 are arranged forward of the furnace B and are adapted to draw. the plates through this furnace and feed them onto a cooling table not shown).

A suitable rack is arranged across the heating chamber 44 from the inlet port 48 to the outlet port 49 for supporting the plates as they pass through the furnace. The rack 52 is preferably of tubularconstruction to permit Water being; passed thercthrough for the purpose of cooling it.

In carl ving out the method of this application the cold plates are first passed onto the conveyor chains 14 at the inlet 32 of the;

furnace A-and are conveyed through the heating chamber 12 of this furnace wherein their entire area is heatedup to a. point slightly below the lower critical temperature of the metal. The plates are then passed out of the furnace A and into the furnace ll, which is heated to from 1600 degrees to 2200 degrees 1*. by a flame from the burners 47. As the plates are passed into the furnace B they are successively passed through from one side to the otl1cr,'into and through the heating chamber 44 and pass out through the outlet or discl'iarge opening 49. The heating chamber 44- is made very narrow so as to expose very narrow portions of the plate or sheet being heat treated to the action of the heat at one time. and the narrower the section of the plate which is exposed to the heating action the better the result obtained. The plates are. cooled as they pass out of the furnace. "That is. the successive sections are cooled in the same order that they are heated.

The present method will produce plates having all the in'ipl'oved characteristics of the plates produced by the While method, and is distinguisl'ied from the lVhile method by lhe preheating operation which permit? the plates to be finally annealed in about half the time required by the lVhite method.

I claim- 7 i i l. The combination with an elongated heating furnace for sheets and plates, l 'ivingmeans for moving plates continuoustherothrough and adapted to heat the tea , meagre heating furnace adapted to heat the whole area of a plate to approximately an even temperature, of a heat treating furnace arranged immediately forward of said heating furnace and adapted to receive the plates from said heating furnace, saidheat treating furnace being provided with a relatively narrow transversely arranged heating chamber adapted to heat successively different narrow sections of said previously heated )lates to a materially higher temperature.

3. A heat treating apparatus for sheets and plates, comprising in combination, an elongated heating furnace having a heating chamber of materially greater size than the plates to be heated and inlet and outlet ports at opposite ends of said chamber, a continuous conveyer arranged to move the plates through said heating chamber, and a heat treating furnace arranged across the outlet port of said heating furnace and adapted to receive the plates therefrom, said treating furnace being provided with a rela- .tively narrow heating chamber over which the plates pass, whereby successively different sections of the previously heated lates are heated to a temperature of at east 1600 degrees Fahrenheit, which is a materially greater temperature than maintained in said heating furnace.

4. A heat treating apparatus for sheets and plates, comprising in combination, an elongated heating furnace having a heating chamber of materially greater size than the plates to be heated and inlet and outlet ports at opposite ends of said chamber, a plurality of combustion chambers below said heating chamber, said combustion chambers, extending inwardly from the opposite sides of said furnace and being alternated with air circulation chambers, the combustion chambers extending from one side of the furnace being arranged in staggered relation with the combustion chambers extending from the other side,of the furnace, and being opposite one of said air circulation chambers, a continuous conveyer arranged to move plates through said heating chamber, and

a heat treating furnace arranged across thev outlet port of said heating furnace and adapted to receive the plates therefrom, said treating furnace being provided with a relatively narrow heating chamber over which the plates pass, whereby successively" different sections of the previously heated plates are heated to a temperature of at least 1600 degrees Fahrenheit, and means for causing such intense heat in the heating chamber of said treating furnace.

5. The method of heat treating rolled steel sheets and plates which consists in heating the whole plate to a temperature below the lower critical temperatuieof the metal, then heating successively different sections of the preheated sheets to a temperature materially above the lower critical temperature of the metal, and cooling the sections of the sheets or plates in the order in which they are heated.

6. The method of heat treating rolled steel sheets and plates which consists in heating substantially the whole plate to a temperature below the .lower critical temperature of the metal, then heating successively different sections of the preheated sheets and plates to a temperature of at least 1600 degrees Fahrenheit, and cooling the heated sections successively inthe order in which they are heated.

7. The method of heat treating rolled steel sheets and plates which consists in heating the plate to a temperature below 7 

